 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal;

 import java.io.BufferedReader ;
 import java.io.File ;
 import java.io.FileInputStream ;
 import java.io.IOException ;
 import java.io.InputStreamReader ;

 import org.eclipse.core.runtime.IPath;
 import org.eclipse.jface.dialogs.ErrorDialog;
 import org.eclipse.jface.dialogs.MessageDialog;
 import org.eclipse.swt.widgets.Shell;
 import org.eclipse.ui.IMemento;
 import org.eclipse.ui.IWorkingSet;
 import org.eclipse.ui.IWorkingSetManager;
 import org.eclipse.ui.WorkbenchException;
 import org.eclipse.ui.XMLMemento;
 import org.osgi.framework.BundleContext;
 import org.osgi.framework.BundleListener;

 /**
  * A working set manager stores working sets and provides property change
  * notification when a working set is added or removed. Working sets are
  * persisted whenever one is added or removed.
  *
  * @see IWorkingSetManager
  * @since 2.0
  */
 public class WorkingSetManager extends AbstractWorkingSetManager implements
         IWorkingSetManager, BundleListener {

     // Working set persistence
 public static final String WORKING_SET_STATE_FILENAME = "workingsets.xml"; //$NON-NLS-1$

     public WorkingSetManager(BundleContext context) {
         super(context);
     }

     /*
      * (non-Javadoc)
      *
      * @see org.eclipse.ui.IWorkingSetManager
      */
     public void addRecentWorkingSet(IWorkingSet workingSet) {
         internalAddRecentWorkingSet(workingSet);
         saveState();
     }

     /*
      * (non-Javadoc)
      *
      * @see org.eclipse.ui.IWorkingSetManager
      */
     public void addWorkingSet(IWorkingSet workingSet) {
         super.addWorkingSet(workingSet);
         saveState();
     }

     /**
      * Returns the file used as the persistence store, or <code>null</code> if
      * there is no available file.
      *
      * @return the file used as the persistence store, or <code>null</code>
      */
     private File getWorkingSetStateFile() {
         IPath path = WorkbenchPlugin.getDefault().getDataLocation();
         if (path == null) {
             return null;
         }
         path = path.append(WORKING_SET_STATE_FILENAME);
         return path.toFile();
     }

     /*
      * (non-Javadoc)
      *
      * @see org.eclipse.ui.IWorkingSetManager
      */
     public void removeWorkingSet(IWorkingSet workingSet) {
         if (internalRemoveWorkingSet(workingSet)) {
             saveState();
         }
     }

     /**
      * Reads the persistence store and creates the working sets stored in it.
      */
     public void restoreState() {
         File stateFile = getWorkingSetStateFile();

         if (stateFile != null && stateFile.exists()) {
             try {
                 FileInputStream input = new FileInputStream (stateFile);
                 BufferedReader reader = new BufferedReader (
                         new InputStreamReader (input, "utf-8")); //$NON-NLS-1$

                 IMemento memento = XMLMemento.createReadRoot(reader);
                 restoreWorkingSetState(memento);
                 restoreMruList(memento);
                 reader.close();
             } catch (IOException e) {
                 MessageDialog
                         .openError(
                                 (Shell) null,
                                 WorkbenchMessages.ProblemRestoringWorkingSetState_title,
                                 WorkbenchMessages.ProblemRestoringWorkingSetState_message);
             } catch (WorkbenchException e) {
                 ErrorDialog
                         .openError(
                                 (Shell) null,
                                 WorkbenchMessages.ProblemRestoringWorkingSetState_title,
                                 WorkbenchMessages.ProblemRestoringWorkingSetState_message,
                                 e.getStatus());
             }
         }
     }

     /**
      * Saves the working sets in the persistence store
      */
     private void saveState() {

         File stateFile = getWorkingSetStateFile();
         if (stateFile == null) {
             return;
         }
         try {
             saveState(stateFile);
         } catch (IOException e) {
             stateFile.delete();
             MessageDialog.openError((Shell) null,
                     WorkbenchMessages.ProblemSavingWorkingSetState_title,
                     WorkbenchMessages.ProblemSavingWorkingSetState_message);
         }
     }

     /**
      * Persists all working sets and fires a property change event for the
      * changed working set. Should only be called by
      * org.eclipse.ui.internal.WorkingSet.
      *
      * @param changedWorkingSet
      * the working set that has changed
      * @param propertyChangeId
      * the changed property. one of CHANGE_WORKING_SET_CONTENT_CHANGE
      * and CHANGE_WORKING_SET_NAME_CHANGE
      */
     public void workingSetChanged(IWorkingSet changedWorkingSet,
             String propertyChangeId, Object oldValue) {
         saveState();
         super.workingSetChanged(changedWorkingSet, propertyChangeId, oldValue);
     }
 }

